Axial-flow piston pump with pivotable cylinder drum

ABSTRACT

An axial-flow piston pump including a pivotable cylinder drum, and an operatively-coupled drive disc which is fixedly supported within a housing and to which pistons are linked through the intermediary of ball joint linkages, the pistons being movably located within the cylinder bores of the drum; and a control deflector member having control recesses whose outlets face towards the cylinder bores, wherein the control deflector member is pivotable by means of an adjusting installation in response to the vertical stroke of the pump, and wherein the cylindricallyshaped rear surface thereof facing away from the control deflector member is supported on a complementary shaped guide surface of the housing which evidences opening connected with suction or, respectively, pressure passageways for the pressure medium which remain in connection with the control recesses for all inclined positions of the control deflector member.

United States Patent [191 Wagenseil et a1.

[ Oct. 28, 1975 AXIAL-FLOW PISTON PUMP WITH PIVOTABLE CYLINDER DRUM [73] Assignee: Hydromatik GmbH, Ulm, Danube,

Germany [22] Filed: Jan. 6, 1975 [21] Appl. N0.: 538,855

[30] Foreign Application Priority Data Jan. 11, 1974 Germany 2401331 [52] US. Cl. 91/504 [51] Int. Cl. FOIB 13/04 [58] Field of Search 91/484, 485, 499, 504-506; 92/12.]

[56] References Cited UNITED STATES PATENTS 3,291,068 12/1966 Wiggenmann 1. 91/505 FOREIGN PATENTS OR APPLICATIONS 973,707 10/1964 United Kingdom 91/507 l/l955 United Kingdom 92/l2.2 5/1958 Germany 92/122 Primary Examiner-William L. Freeh Attorney, Agent, or FirmWaters, Schwartz & Nissen [57] ABSTRACT An axial-flow piston pump including a pivotable cylinder drum, and an operatively-coupled drive disc which is fixedly supported within a housing and to which pistons are linked through the intermediary of ball joint linkages, the pistons being movably located within the cylinder bores of the drum; and a control deflector member having control recesses whose outlets face towards the cylinder bores, wherein the control deflector member is pivotable by means of an adjusting installation in response to the vertical stroke of the pump, and wherein the cylindrically-shaped rear surface thereof facing away from the control deflector member is supported on a complementary shaped guide surface of the housing which evidences opening connected with suction or, respectively, pressure passageways for the pressure medium which remain in connection with the control recesses for all inclined positions of the control deflector member.

1 Claim, 4 Drawing Figures US. Patent 0a. 28, 1975 Sheet 3 of3 3,915,069

FIGA

FIELD OF THE INVENTION The present invention relates to an axial-flow piston AXIAL-FLOW pump including a pivotable cylinder drum, and an operatively-coupled drive disc which is fixedly sup-' ported within a housing and to which pistons are linked through the intermediary of ball joint linkages, the pistons being movably located within the cylinder bores of the drum; and a control deflector member having control recesses whose outlets face towards the cylinder bores, wherein the control deflector member is pivotable by means of an adjusting installation in response to the vertical stroke of the pump, wherein the cylindrically-shaped rear surface thereof facing away from the control deflector member is supported on a complementary shaped guide surface of the housing which evidences opening connected with suction or, respectively, pressure passageways for' the pressure medium which remains in connection with the control recesses for all inclined positions of the control deflector member. u

DISCUSSION or THE PRIORLARTI In known machines of this type (German Published Patent Specification No. 1,017,468) the control recesses and the passageways for the inlet ahd outlet of the pressure medium are identically shaped. This is not the result of not only manufacturing reasons, but to also permit the utilization of such types of machines inboth rotating directions thereof, as either pumps or m'otors. Hereby, the openings in the guide surface of the housing which areconnected with, respectively the suction and pressure passageways for, respectively, the inlet and outlet of the pressure medium, are so shaped that, within the overall pivoting range, these openingsare sealed off from the interior chamber of the machine housing by the control deflector member.

The disadvantage of such a construction, as set forth hereinabove, consists of in that the flow' through openings between the control deflector member and the guide surface are to small so as to be able to aspirate the pressure medium from a tank under atmospheric pressure without excessive rotational'speed losses when the machine is to be employed as a self-priming pump in an open operating circuit. The flow-through openings thereby cannot be enlarged as desired, since the pressure loads acting on the rear surface of the coritfol deflector member facing towards the guide surface may not become larger than the forces which are exerted by the pistons through the cylinder drum on the control deflector member, in effect meaning, on the front side of the control deflector member. This results in a lifting of the control deflector member from its associated guide surface. A further problem which is encountered lies in the high level of operating noises, which are caused by the throttling effects in the suction area and the consequent inadequate volumetric filling of the cyl inder bores. I

In axial-flow piston machines of other types of construction, which are exclusively employed aspumps, (German Published Patent Specification No. 1,291 ,632) it is known that the control recesses formed in the control deflector member be essentially larger sized on the suction side than on the pressure side. Herewith, there may be namely reduced the pressure i'witli the suction passageway. r

losses during aspiration of the pressure medium, nevertheless, through the outlets of the cylinder bores leading'to the control deflector member, there is still afforded the undesired throttling effect and consequent noise development, when'tlie: outlet openings are correlated in cross-section to the control recesses on the pressure side or; on the;other hand, when the outlets are'correlated in cross-section to the control recesses on the suction side, the the'pressure forces exerted on the control deflector member become so large, that auxiliary clamping means m'ust be provided in order to avoid the lifting up of the control deflector member. In the last instance, with the arrangement of auxiliary clamping means, the application of an axial-flow piston pump of the above-mentioned type, meaning in effect, with a control deflector member, is no longer possible,

since this results in a much too complicated and thereby impractical solution, and fails to provide a sealingoh the pressure side between the control deflector member and its associated guide surface.

' In order to effect the improvement of the suction output and the reduction in noise development; it is known in an angled-disc pump (German Laid-Open Patent Specification No. 2,213,400) to provide two inlet openings on the control deflector member which are located on concentric circles, and which extend over approximately the same angle, and to concurrently form'on the cylinder bore two apertures 'of, respectively, differently sized cross'sections and which-are located on concentric arcuate segments. Hereby, the aperttir'es having the smaller cross-sections operate in 'conjunction with the inlet opening on the inner circle,

which is connected with the interior of the housing by means of a passageway; and. the apertures having the larger cross-section's operate in conjunction with .the "inlet opening on the outer circle, which is connected The foregoing has the drawback that there are provided relatively unsatisfactory added slits in the control deflector member and in the bores of the cylinder drum. The utilization of pumps of the above-mentioned type is not possible, since the control deflector member becomes excessively weakened through the additional bbres, and on the pressure side, due to the additional apertures of the cylinder bore, the lifting forces acting on the control deflector member are undesirably increased, as previously mentioned hereinabove.

Finally, an inclined or angled-disc axial-flow piston pump is known (German Published Patent Specification No. 1,653,417), in which the control deflector member is broken through on the suction side, and in which aspiration is effected through the openings of the cylinder bore in the cylinder drum directly from the interior chamber or cavity of the housing. This has the drawback that the broken-through control deflector surface exerts an influence on the operating properties of the pump, and the control plateor disc is weakened. Thus, also this solution cannot come into consideration in connection with pumps of the above-mentioned type incorporating control deflector member with which there engages the. adjusting installation.

SUMMARY OF THE INVENTION Accordingly, it is an object of the present invention to so improve the pressure medium inlet for an axialflow piston engine of the above-mentioned type, which operates exclusively as a pump in a self-priming operation whereby, at a reduced noise level operation and good volumetric filling through an increase in the suction cross-sections it is possible to prevent weakening of the control deflector member and, nevertheless, concurrently facilitate leakage oil removal from the housing inner chamber or cavity.

The foregoing object of the invention is solved in a surprisingly simple manner in a pump of the abovementioned type, in which the opening in the guide surface which is connected with the suction passageway is enlarged to such an extent so as to conform to at least surface extension of the associated control recesses, and in all inclined positions of the control deflector member, the projection of the control recesses on the guide surface are fully covered, as well as the housing cavity is continually connected with the suction passageway, in that there remains uncovered a portion of the opening through the control deflector member. Accordingly, by means of inventive solution of the set task, there is no weakening of the control deflector member through otherwise required additional bores in the control deflector member leading to the housing cavity. The control recesses maintain their symmetrical positions and are equally large, whereby no undesirable additional pressure or lifting forces will act on the control deflector member. Consideration is given by the invention to the circumstance that, on the suction side the determinative restrictive location forming transition between the suction aperture and the connection to the control recesses in the control deflector body need not be sealed with respect to the inner cavity of the housing. The suction cross-section is practically equal for all inclined positions of the control deflector body since, by means the inventively constructed opening in the guide surface communicating with the suction passageway connected aperture in the guide surface, the position of the control deflector member and thereby the control recesses on the suction side with respect to this opening, are without influence on the suction cross-section.

Since, inventively, the opening in the guide surface on the suction side of the pump is continually connected with. the housing cavity, the pressure means inlet may also be directly effected, in a known manner, through a housing cavity (compare with German Published Patent Specification No. 1,653,417).

BRIEF DESCRIPTION OF THE DRAWINGS Reference may now be had to an exemplary embodiment of the invention, taken in conjunction with the ac companying drawings; in which:

FIG. 1 schematically illustrates a cross-section through an axial-flow piston pump according to the invention taken along pivot plane thereof;

FIG. 2 is a part section taken along line l-l in FIG.

FIG. 3 is a plan view onto the control deflector surface of the control deflector member; and

FIG. 4 is a part section taken along line lllI in, respectively, FIGS. 2 and 3.

DETAILED DESCRIPTION The axial-flow piston pump which is illustrated in FIG. 1 includes a drive shaft 3 which is supported by means of a ball bearing 1 in a housing 2, and which shaft integrally carries a drive plate or disc 4. Supported on the drive plate 4 through the intermediary of ball swivel joints 5 are the piston rods 6 of piston 7. The pistons 7 move within cylinder bores 8 of a cylinder drum 9. The cylinder drum 9 is adapted to be placed into rotation by the drive shaft 3 through the drive plate 4 and the pistons 7. The extent of lifting of the pistons 7 is determined in accordance with the angle of inclination of the cylinder drum axis 10 relative to the rotational axis 11 of the shaft 3. The cylinder drum 9 is centered by means of a centering journal 13, the latter of which is supported by a sphere 12 on the drive plate 4, and is supported, -in the loaded condition of the pump under the effect of the pressure medium forces and in the unloaded condition of the pump under only the force of the pressure spring 14 located between the journal 13 and the cylinder drum 9, -against a control deflector member 15, and which itself is supported on a cylindrically-surface shaped guide surface 16 of the pump housing portion 17. For effecting a variation in the angle of inclination of the axis 10 of the cylinder drum 9 with respect to the shaft axis 11, and thereby a change in the lifting volume of the pistons 7 in the cylinder bores 8, an adjusting trunnion 18 engages the control deflector member 15, which is rigidly connected with an adjusting rod 19, the latter of which is displaceably supported within a bore 20 in the pump housing portion 17. A setting mechanism (not shown) engages the adjusting rod 19, by means of which the adjusting rod 19 may be displaced in a longitudinal direction whereby the trunnion 18 displaces the control deflector member 15 along the cylindrically-shaped guide surface 16 with resultant pivoting of the cylinder drum 9 about the pivot axis 21.

In the control deflector member 15 there are provided, as may be ascertained in closer detail from FIGS. 2 through 4 of the drawings, inlet and outlet flow passageways 22, 23 which connect the cylinder bores 8 through the openings 24, and the control recesses 25, 2.6 (FIG. 3) formed in the control deflector surface 27 of the control deflector member 15, with the openings 28, 29, of, respectively, the suction passageway 30 and pressure passageway 31 in the guide surface 16. As may be more readily ascertained from FIG. 3, the opening 32 of the passageway 23 has an elongate configuration on the pressure side so that, at each angular position of the control deflector member 15, the opening 29 in the guide surface 16 is covered. On suction side the passageway 22 has a cross-section which, along its entire length, corresponds to at least the surface extension of the control recesses 25. The opening 28 is constructed so large, as may be ascertained from FIGS. 3 and 4, whereby the projection of the control recesses in the guide surface 16 always lies within the surface extension of the opening 28. In the position of the control deflector member 15, as shown in FIGS. 3 and 4, the opening 28 with the parts 33, 34 projects outwardly beyond the control deflector member 15, and is not covered by the latter, so as-to form a connection with the housing inner chamber or cavity 35. Since the connection to the housing cavity 35 is provided at every position of the control deflector member 15, the leakage portion of the pressure medium collecting in the housing cavity is aspirated so as to afford the possibility that the aspiration of the entire pressure medium may be effi fected through the housing cavity 35 when for this pur- While there has been shown what is considered to be the preferred embodiment of the invention, it will be obvious that modifications may be made which come within the scope of the disclosure of the specification.

What is claimed is:

1. In an axial-flow piston pump having a pivotable cylinder drum having a plurality of cylinder bores; a housing encompassing said cylinder drum; a drive disc fixedly supported in said housing and adapted to be op eratively driven; a plurality of pistons reciprocably mounted in said cylinder bores; ball joint means linking said pistons to said drive disc; a control deflector member having control recesses facing .the outlets of said cylinder bores; and adjusting means for pivoting said control deflector member for determining the lifting setting of said pump; said housing having a guide surface of generally cylindrical configuration supporting the complementary shaped rear surface of said control pivoted positions of said control deflector member fully covering the projection of the control recesses on the guide surface and concurrently continually connect the housing cavity with the suction passageway in that a portion of the opening remains uncovered by said con- .trol deflector member. 

1. In an axial-flow piston pump having a pivotable cylinder drum having a plurality of cylinder bores; a housing encompassing said cylinder drum; a drive disc fixedly supported in said housing and adapted to be operatively driven; a plurality of pistons reciprocably mounted in said cylinder bores; ball joint means linking said pistons to said drive disc; a control deflector member having control recesses facing the outlets of said cylinder bores; and adjusting means for pivoting said control deflector member for determining the lifting setting of said pump; said housing having a guide surface of generally cylindrical configuration supporting the complementary shaped rear surface of saiD control deflector member opposite the control surface thereof, said guide surface having openings communicating with, respectively, suction and pressure passageways for a pressure medium, said openings being in communication with said control recesses for all inclined positions of said control deflector member, the improvement comprising: the opening in said guide surface communicating with said suction passageway being enlarged to at least an extent to conform to the surface extension of the associated control recess, and in all pivoted positions of said control deflector member fully covering the projection of the control recesses on the guide surface and concurrently continually connect the housing cavity with the suction passageway in that a portion of the opening remains uncovered by said control deflector member. 